It only happens every once in a while, if you then press the reload button (top of the three blue recaptcha buttons) it shows a captcha so it is not "urgent" as such although you have to press reload to "bypass" the error. Perhaps a short note saying "press reload" should be added to the confirmation code text on the right side of the captcha.

If you google "google recaptcha march 31st" you will find news stories about it so apparently it will stop working and you need to upgrade. You don't get the warning each time, seems random perhaps 1 in 10 times. If you then refresh it (blue recaptcha refresh button) you get the normal images.